航空发动机燃烧室燃烧过程与排放物生成的反应动力学数值模拟

选用正癸烷作为航空煤油的替代燃料,建立了正癸烷的化学反应详细机理与简化机理(包括50种组分,118个基元反应).分别采用详细机理与简化机理对正癸烷在激波管中的着火延迟时间、在预混燃烧炉内的燃烧过程进行了数值计算,并与实验结果进行了对比分析.同时,耦合该简化机理与CFD计算软件Fluent,对某型航空发动机环管形燃烧室中单个火焰筒内流动特性与燃烧过程、排放物及活性中间组分生成的反应动力学特性进行了详细分析,并与采用C12H23为燃料的单步反应机理的计算结果进行了对比分析.结果表明:采用简化机理计算得到的着火延迟时间、反应物与各主要生成物摩尔分数的整体变化趋势与实验数据吻合较好；与采用C12H23为燃料的单步反应机理相比,采用正癸烷为替代燃料的简化反应机理计算得到的温度场分布更符合实际,其出口平均温度亦更为接近燃烧室出口设计温度；同时,能更为详细了解燃料低温裂解过程及裂解产物、中间产物及主要排放物的生成规律.

Reaction kinetic numerical simulation of combustion process and emission formation in aero-engine combustor

A detailed mechanism and a reduced reaction mechanism (including 50 species and 118 reactions) of n-decane which was chosen as a surrogate fuel for kerosene were built.The ignition delay time of this surrogate fuel in the shock tube and the process of premixed combustion in the premixed burner were simulated by adopting the detailed and reduced reaction mechanisms,and the simulated results were compared with the experimental data.Furthermore,the flow characteristics and the reaction kinetic characteristics of combustion process and the formation of emissions and active species in a tube of the annular tube combustor were analyzed by combining this reduced reaction mechanism with the CFD computational software(Fluent),and the computational results were compared with that of the global reaction mechanism of C₁₂H₂₃ fuel.The results show that the ignition delay time,the shape of the profiles of the mole fractions of the reactants,the major combustion products simulated using the reduced mechanism agree well with the experimental data.Furthermore,compared with the global reaction mechanism of C₁₂H₂₃ fuel,when adopting the reduced reaction mechanism of n- decane,temperature field accords well with the practical situation,and the computational outlet temperature is closer to the design outlet temperature of the combustor.At the same time,the process of fuel low temperature decomposition and formations of pyrolysis products,active species and main emissions are better detailedly understood.